<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<script src="./node_modules/vue/dist/vue.js"></script>
<body>
<div id="app">

    {{birth}}
</div>

<script>
    const app = new Vue({
        el:"#app",
        data:{
            birthday:1919923128818,
        },
        computed:{
            birth(){
                const d = new Date(this.birthday);
                return d.getFullYear()+"-"+(d.getMonth()+1)+"-"+d.getDate();
            }
        }
    })
</script>



</body>
</html>